Process of rendering metal nonoxidizable and the metal



re Drag.

To all whomz't may concern:

' Bait known that I, Warmer J. Knnr, a

citizen of the United States of America, residin at Detroit, in the county of Wayne and tate of Michigan, have invented certain new and useful 1m royements in Procasses of Rendering Meta Nonoxidizable and the Metal, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to a process for rendering certain metals, such as steel, wrought iron, cast iron and other ferrous alloys nonoxidizable, and capable of withstanding high temperature without deterioriation.

it also relates to-the same process applied to copper and similar "metals, changing the surfaces or outer portion to what appears to be aluminum bronze, etc., and less oxidizable than the metals before treating.

The invention alsoconsists in rendering steel iron and ferrous alloys either fully incapable of permanent elongations and distortions when exposed to intense heat, or less subject thereto than the metals before treatment.

The invention also results in reducing the co-eficient of expansion of the treated metals. I

The invention also includes the products that are so obtained.

Such compound is of difierent physical a pearance and characteristics than either 0? the components thereof. It is nonexidizable not onlyin ordinary or atmospheric temperatures but also at temperatures above the melting point of aluminum. It is also refractory at these temperatures and does not yield to heat which melts either of the components.

In general terms the process consists first in bringing the metal to be treated into contactwith molten aluminum and at the temperature substantially of the latter, a suitable flux being provided if necessary, where-.

by the aluminum coats the metal. At this point the treated metal is aluminum-coated, the same as if tinned or tin-coated, or as if galvanized or plated. The next step consists in efiecting an intimate union or compound of the metal and its coat. This is accomplished by heating the coated metal to a comparatively high degree of temperature and maintaining it at such temperature until the aluminum enters into an intimate and Application and June a, 1915. eel-m1 no. eater-.-

st able combination with the metal, such union being physical or chemical, or both, dependent on the metal treated. Durin this step the coat disappears and a compoun appears that'does not have the ap earance or physical characteristics of either t e metal or the aluminum; a

As one practical way of carrying out the process, the metal to be treated must be free from oxide and clean. Sand blasting is satisfactory for this. The surface may be coated with a suitable flux, which may be a solution of borax with which the metal is brushed or washed. A bath of molten aluminum which is kept as near the melting point as practicable, that is between 625 degrees and 700 degrees centigrade, is provided in which the metal to be treated is immersed.-

it is kept there until of the same temperature or approximately the same temperature as the ath which may be judgfd by its having the same rose color as the ath. In

the case of thin sheet iron or wire the latter can be dipped in and out uickly. If any drops of aluminum remain a r the removal from the bath the article may be struck or vibrated to remove them.

The metal thus coated with aluminum is then put throu h the second part of the process. A mu e is heated to about 1100 de- 'grees centigrade, and the coated metal placed therein, the door being left open. To utilize the full capacity of the mufiie, suflicient pieces or articles of metal are dipped or coated first in order to fill the mufie;

As soon as the pieces of metal or articles reach the right temperature, the aluminum apparently sinks in or forms a stable union or combination with the adjacent metal and the process is complete, the treated article having an outer layer that is neither aluminum nor the original metal.

The treated metal from this process is different from the article or metal to which a C(Lat or layer of aluminum has been applied as y resists high temperatures, even those sufiicient to attack and reduce the exposed or uncoated parts, if there be any.

Because of its resistance to heat the metal does not tend to be permanently elongated or distorted under the influence of heat. It also has a lower co-eificient of expansion.

By re-dipping the metal, and in such instance itis not necessary to bring the. metal the first step. It is not afi'ected ap- .preoiably by the atmosphere and successfully ess, that is, the metal compound which is formed by the union of the aluminum with the metal treated, does not present a pure aluminum surface as is the result when the metal is merely coated. Unlike galvanizing, tinning or aluminum coating processses which prevent oxidization only in atmospheric temperature and which in the case of the aluminum coating, are inafl'ective when the metal is exposed above red heat for any length of time, this process produces a new metal compound or composition, that does not have a surface with the characteristic either of the treated metal or of the aluminum, but one which is entirely different in appearance from either and which is highly refractory and so far as can be ascertained, practically indes'tructable. The product further is entirely different from the ordinary aluminum-ferrous alloy in that such an alloy melts at a temperature far below that of steel, while in this instance, heat which would destroy for example, does not destroy the portion of the steel that has thus been treated. It has none of the properties of the alloy or of either of the component metals and is nonoxidizable at all temperatures so far as tried.

It is to be understood that the term nonoxidizable, is in a sense, comparative, as While the product is to all intents and under ordinary tests nonoxidizable, it is not as yet fully proved that such action may not be evident in time.

What I claim is 1. The me hod of producing a non-porous and highly-refractory surface on metals to produce a core and surface formation, and

wherein the surface has a heat-resisting characteristic of greater value than that of the core, which consists in developing a surface from the core metal and aluminum by a stage operation in which the metal is initially coated with molten aluminum by dipping, with both metals having a temperature value during the coating operation at least equal to that of the melting point temperature of the aluminum, then removing the coated metal from the aluminum bath to produce an embryo product, then removing the excess of aluminum from, the prod-v for a period of time suflicient to complete the product with the product havinga nonoxidizable surface of compound formation, of non-porous characteristic, and of heat resisting value greater than that required for the reduction of aluminum or of the metal being treated, and which constitutes the core of the product.

2. The method of producing a non-porous highly-refractory surface on steel, iron and like ferric compounds to produce a product wherein such metal forms the core of the product, and wherein the surface will resist heat temperatures in excess of those capable of reducing the metal forming the core, such method consisting in developing the surface from the core metal and aluminum by a stage operation in which the core metal is initially coated with molten aluminum by dipping the core metal in an aluminum bath and with both metals having a temperature value at least equal'to that of the melting point temperature of the aluminum during the dipping operation, thereby producing a coating upon the core metal; then removing the coated core metal from the aluminum bath to produce an embryo product; then removing the excess of aluminum from the product by product manipulation, and then producing the surface by subjecting the embryo product to the action of heat of a temperature value considerably above that of the melting point of the bath aluminum and in the presence of air to provide a heat application differing in characteristic from that of the bath and for a period of time sufiicient to complete the product, such completed product having the characteristics of a surface integrally and permanently united to the core of being non-porous and non-oxidized, and of heat resisting value greater than that required for the reduction of aluminum or of the metal of the core of the product.

In testimony whereof I afiix my signature in presence of two witnesses.

WILLIAM J. KEEP. Witnesses:

ANNA M. Donn, KARLH. BUTLER. 

